The present invention relates to new 4,4xe2x80x2-diaminostilbene-2,2xe2x80x2-disulfonic acid compounds which are useful as fluorescent whitening agents or for removing stain in photographic materials.
In WO 96/00221, there are described optical brightening agents for textiles, paper etc. The disclosed compounds have the formula: 
in which Ra and Rb are the same or different and each has the formula xe2x80x94NRcRd in which Rc is hydrogen; C1-6alkyl which is optionally substituted by at least one of mercapto, C1-C6thioalkyl, OH and SO3Mxe2x80x2 in which Mxe2x80x2 is hydrogen, a colourless cation or an amine-derived cation; or xe2x80x94Re(CO2Mxe2x80x2)x in which Re is an aliphatic moiety having 1-6 carbon atoms, those valencies not bonded with groups CO2Mxe2x80x2 being bonded with at least one of hydrogen, mercapto, C1-C6thioalkyl, OH and SO3Mxe2x80x2 in which Mxe2x80x2 has its previous significance and x is an integer from 1 to 4, provided that, when Rc is C1-C6alkyl which is optionally substituted by at least one of mercapto, C1-C6thioalkyl, OH and SO3Mxe2x80x2, Rc is substituted with at least both of OH and SO3Mxe2x80x2; Rd is Rc, hydrogen or C3-C6alkyl, provided that Rc and Rd cannot both be hydrogen and that, when one of Rc and Rd is hydrogen, the other cannot be xe2x80x94(NHCH2CO2H); or Rc and Rd, together with the nitrogen atom, form a ring having from 5-6 members only, one of which is heterocyclic, which ring is singly substituted with xe2x80x94COOMxe2x80x2 or xe2x80x94SO3Mxe2x80x2; and each Rf, independently, is hydrogen, methyl, C1-C6alkoxy or halogen.
Furthermore, WO 98/42685 describes similar compounds having the formula: 
in which X is O or, preferably, NH; M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; each R1, independently, is an amino acid residue from which a hydrogen atom on the amino group has been removed; n is 1 or 2; and each R2, independently, is hydrogen, C1-C3alkyl, halogen, cyano, COOR in which R is hydrogen or C1-C3alkyl, CONHxe2x80x94R in which R has its previous significance, SO2NHxe2x80x94R in which R has its previous significance, NHxe2x80x94COR in which R has its previous significance, SO3M in which M has its previous significance or, when n is 1, R2 can also be COxe2x80x94R3 in which R3 is C1-C3alkyl or phenyl, certain compounds being excluded, and their use as fluorescent whitening agents.
A new class of 4,4xe2x80x2-diaminostilbene-2,2xe2x80x2-disulfonic acid compounds has now been found most of which are useful as fluorescent whitening agents and which have superior properties to, and are more readily prepared than the compounds disclosed in WO 96/00221 and in WO 98/42685. Furthermore, the new compounds are useful for removing stain in photographic materials.
Accordingly, the present invention provides new compounds having the formula: 
wherein each
R1 represents, independently, a linear C1-C4-alkylene residue which is unsubstituted or substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C4-alkyl, or an amino acid residue from which a hydrogen atom on the amino group has been removed; each
R2 represents, independently, a linear C1-C4-alkylene residue which is unsubstituted or substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C1-C4alkyl, xe2x80x94CO2M, CO2C1-C4-alkyl SO3M or phenoxy which is unsubstituted or substituted by halogen, C1-C4-alkyl or C1-C4-alkoxy, xe2x80x94CO2M or xe2x80x94CO2C1-C4-alkyl, NH2 or mono- or disubstituted amino; or phenyl which is unsubstituted or substituted by 1 to 3 SO3M, SO2NHC1-C4-alkyl, xe2x80x94SO2NH2, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl xe2x80x94CONH2, xe2x80x94CONHC1-C4-alkyl, xe2x80x94NHCOC1-C4-alkyl or mono- or disubstituted amino groups; each
R3 represents, independently, hydrogen, C1-C4-alkyl, halogen, cyano, SO3M, xe2x80x94SO2NH2, SO2NHC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, xe2x80x94CONH2, xe2x80x94CONHC1-C4-alkyl, or xe2x80x94NHCOC1-C4-alkyl;
M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine and
m is an integer of 1 to 3.
Within the scope of the compounds of formula (1) both of the R1 groups, the R2 groups and the R3 groups are preferably identical.
Further preferred compounds of formula (1) are those in which each of the amino acid residues R1 is the same and each has the formula xe2x80x94NHxe2x80x94CH(CO2H)xe2x80x94R4 in which R4 is hydrogen or a group having the formula xe2x80x94CHR5R6 in which R5 and R6, independently, are hydrogen or C1-4-alkyl optionally substituted by one or two substituents selected from hydroxy, thio, methylthio, amino, carboxy, sulfo, phenyl, 4-hydroxyphenyl, 3,5-diiodo-4-hydroxyphenyl, xcex2-indolyl, xcex2-imidazolyl and NHxe2x95x90C(NH2)NHxe2x80x94.
Particularly useful compounds of formula (1) are those in which the amino acid from which the amino acid residues R1 are derived is glycine, alanine, sarcosine, serine, cysteine, phenylalanine, tyrosine (4-hyroxyphenylalanine), diiodotyrosine, tryptophan (xcex2-indolyalanine), histidine ((xcex2-imidazolylalanine), xcex1-aminobutyric acid, methionine, valine (xcex1-aminoisovaleric acid), norvaline, leucine (xcex1-aminoisocaproic acid), isoleucine (xcex1-amino-xcex2-methylvaleric acid), norleucine (xcex1-amino-n-caproic acid), arginine, ornithine (xcex1,xcex4-diaminovaleric acid), lysine (xcex1,xcex5-diaminocaproic acid), aspartic acid (aminosuccinic acid), glutamic acid (xcex1-aminoglutaric acid), threonine, hydroxyglutamic acid or taurine, or a mixture or an optical isomer thereof.
Especially preferred compounds are those in which the amino acid from which the amino acid residues R1 are derived is sarcosine, taurine, glutamic acid or aspartic acid, aspartic acid or iminodiacetic acid being the most desirable.
Further preferred compounds of formula (1) are those in which R1 is a linear C1-C4-alkylene residue which is unsubstituted or substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C4-alkyl, especially those in which R1 is a linear C1-C4-alkylene residue which is unsubstituted or substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy and, most preferably, those in which R1 is a linear C1-C4-alkylene residue which is substituted by hydroxy or C1-C4-alkoxy, M being as previously defined.
With regard to the residue R2, this is preferably a linear C1-C4-alkylene residue which is unsubstituted or substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, SO3M, phenoxy which is unsubstituted or substituted by halogen, C1-C4-alkyl, C1-C4-alkoxy, xe2x80x94CO2M or xe2x80x94CO2C1-C4-alkyl, NH2 or mono- or disubstituted amino, most preferably, a methylene, ethylene or propylene residue which is substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, SO3M or di-C1-C4-alkylamino.
Compounds of particular interest are those in which R2 is hydoxyethyl, hydroxypropyl, ethoxyethyl, hydroxyethoxyethyl, methoxyethoxyethyl, an acetic or propionic acid residue or methyl or ethyl esters thereof, an ethyl or methyl acetate, dimethylaminoethyl or ethyl sulphonic acid or the sodium salt thereof, an hydoxyethyl or a sodium acetate residue being most preferred.
Further interesting compounds are those in which each R2 is phenyl which is unsubstituted or substituted by 1 to 3 SO3M, SO2NHC1-C4-alkyl, xe2x80x94SO2NH2, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, xe2x80x94CONH2, xe2x80x94CONHC1-C4-alkyl, xe2x80x94NHCOC1-C4-alkyl or mono- or disubstituted amino groups.
Of especial interest are compounds in which each R2 is phenyl which is unsubstituted or substituted by one SO3M, xe2x80x94SO2NH2 or xe2x80x94NHCOC1-C4-alkyl group, however, the phenyl group is preferably unsubstituted.
Further preferred compounds of formula (1) are those in which each R3 residue represents hydrogen, C1-C4-alkyl, halogen, cyano, SO3M, xe2x80x94SO2NH2, SO2NHC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, xe2x80x94CONH2, xe2x80x94CONHC1-C4-alkyl, or xe2x80x94NHCOC1-C4-alkyl, those in which R3 represents hydrogen being most preferred.
In the formulae of the above compounds, M is preferably hydrogen, Na, K, Ca, Mg, ammonium, mono-, di-, tri- or tetra-C1-C4alkylammonium, mono-, di- or tri-C1-C4-hydroxyalkylammonium or ammonium that is di- or tri-substituted with a mixture of C1-C4-alkyl and C1-C4-hydroxyalkyl groups, especially hydrogen or Na and m is preferably 1.
Compounds of most particular interest are those of the formula: 
The compounds of formula (1) may be produced by reacting, under known reaction conditions, cyan uric chloride, successively, in any desired sequence, with each of 4,4xe2x80x2-diamino-2,2xe2x80x2-stilbene disulfonic acid, an amino compound capable of introducing a group 
in which R2, R3 and m have their previous significance, and a compound capable of introducing a group R1, in which R1 has its previous significance.
Preferably, 2 males of cyanuric chloride are initially reacted with 1 mole of 4,4xe2x80x2-diamino-2,2xe2x80x2-stilbene disulfonic acid, then with an amino compound capable of introducing a group 
in which R2, R3 and m have their previous significance, and, finally, with a compound capable of introducing a group R1, in which R1 has its previous significance.
Consequently, a further aspect of the invention is a compound of formula: 
in which R2, R3, M and m are as previously defined.
Within the scope of the compounds of formula (5) both of the two R2 groups and the two R3 groups are preferably identical.
With regard to the residue R2, this is preferably a methylene, ethylene or propylene residue which is substituted by hydroxy, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-hydroxy- or alkoxy-alkoxy, xe2x80x94OCOM, xe2x80x94OCOC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, SO3M or di-C1-C4-alkylamino.
Compounds of particular interest are those in which R2 is hydoxyethyl, hydroxypropyl, ethoxyethyl, hydroxyethoxyethyl, methoxyethoxyethyl, an acetic or prop ionic acid residue or methyl or ethyl esters thereof, an ethyl or methyl acetate, dimethylaminoethyl or ethyl sulphonic acid or the sodium salt thereof, hydoxyethyl or a sodium acetate residue being, most preferred.
Further interesting compounds are those in which each R2 is phenyl which is unsubstituted or substituted by 1 to 3 SO3M, SO2NHC1-C4-alkyl, xe2x80x94SO2NH2, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, CONH2, xe2x80x94CONHC1-C1-alkyl, xe2x80x94NHCOC1-C4-alkyl or mono- or disubstituted amino groups.
Of especial interest are compounds in which each R2 is phenyl which is unsubstituted or substituted by one SO3M, xe2x80x94SO2NH2 or xe2x80x94NHCOC1-C4-alkyl group, however, the phenyl group is preferably unsubstituted.
Further preferred compounds of formula (5) are those in which each R3 residue represents hydrogen, C1-C4-alkyl, halogen, cyano, SO3M, xe2x80x94SO2NH2, SO2NHC1-C4-alkyl, xe2x80x94CO2M, xe2x80x94CO2C1-C4-alkyl, xe2x80x94CONH2, xe2x80x94CONHC1-C4-alkyl, or xe2x80x94NHCOC1-C4-alkyl, those in which R3 represents hydrogen being most preferred.
In the formulae of the above compounds, M is preferably hydrogen, Na, K, Ca, Mg, ammonium, mono-, di-, tri- or tetra-C1-C4alkylammonium, mono-, di- or tri-C1-C4-hydroxyalkylammonium or ammonium that is di- or tri-substituted with a mixture of C1-C4-alkyl and C1-C4-hydroxyalkyl groups, especially hydrogen or Na and m is preferably 1.
The starting materials are known compounds which are readily available.
A further aspect of the invention is a composition for whitening synthetic or natural organic materials or for removing stain from photographic materials, which contains water, a fluorescent whitening agent of formula (1) and, optionally, auxiliaries.
More specifically, such brightener compositions contain water and, in each case based on the weight of the formulation, from 3 to 25% by weight, preferably from 5 to 15% by weight of the above defined fluorescent whitening agent mixture and also 0 to 60%, preferably 5 to 50% by weight, of auxiliaries.
Suitable auxiliaries include, for example, anionic or non-ionic dispersants from the class of ethylene oxide adducts with fatty alcohols, higher fatty acids or alkyl phenols or ethylenediamine ethylene oxide-propylene oxide adducts, copolymers of N-vinylpyrrolidone with 3-vinylpropionic acid, water retention aids, such as ethylene glycol, glycerol or sorbitol, or biocides.
Most of the compounds of formula (1) are excellent fluorescent whitening agents for synthetic or natural substrates such as textiles and, in particular, for paper and also in detergent compositions.
Accordingly, the present invention further provides a method for the fluorescent whitening of a substrate comprising contacting the substrate with a compound having the formula (1).
When used for the fluorescent whitening of paper, the compound of formula (1) according to the present invention may be applied to the paper substrate in the form of a paper coating composition, or directly in the size press.
In one preferred aspect, the present invention provides a method for the fluorescent whitening of a paper surface, comprising contacting the paper surface with a coating composition comprising a white pigment; a binder dispersion; optionally a water-soluble co-binder; and sufficient of a fluorescent whitening agent having the formula (1) according to the present invention, to ensure that the treated paper contains 0.01 to 1% by weight, based on the white pigment, of a fluorescent whitening agent having the formula (1).
As the white pigment component of the paper coating composition used according to the method of the present invention, there are preferred inorganic pigments, e.g., aluminium or magnesium silicates, such as China clay and kaolin and, further, barium sulfate, satin white, titanium dioxide, calcium carbonate (chalk) or talcum; as well as white organic pigments.
The paper coating compositions used according to the method of the present invention may contain, as binder, inter alia, plastics dispersions based on copolymers of butadiene/styrene, acrylonitrile/butadiene/styrene, acrylic acid esters, acrylic acid esters/styrene/acrylonitrile, ethylene/vinyl chloride and ethylene/vinyl acetate; or homopolymers, such as polyvinyl chloride, polyvinylidene chloride, polyethylene and polyvinyl acetate or polyurethanes. A preferred binder consists of styrene/butyl acrylate or styrene/butadiene/acrylic acid copolymers or styrene/butadiene rubbers. Other polymer latices are described, for example, in U.S. Pat. Nos. 3,265,654, 3,657,174, 3,547,899 and 3,240,740.
The optional water-soluble protective colloid may be, e.g., soya protein, casein, carboxymethylcellulose, natural or modified starch, chitosan or a derivative thereof or, especially, polyvinyl alcohol. The preferred polyvinyl alcohol protective colloid component may have a wide range of saponification levels and molecular weights, e.g. a saponification level ranging from 40 to 100; and an average molecular weight ranging from 10,000 to 100,000.
Recipes for coating compositions for paper are described, for example, in J. P. Casey xe2x80x9cPulp and Paperxe2x80x9d; Chemistry and Chemical Technology, 2nd edition, Volume III, pages1684-1649 and in xe2x80x9cPulp and Paper Manufacturexe2x80x9d, 2nd and 5th edition, Volume II, page497 (McGraw-Hill).
The paper coating compositions used according to the method of the present invention preferably contain 10 to 70% by weight of a white pigment. The binder is preferably used in an amount which is sufficient to make the dry content of polymeric compound up to 1 to 30% by weight, preferably 5 to 25% by weight, of the white pigment. The amount of fluorescent brightener preparation used according to the invention is calculated so that the fluorescent brightener is preferably present in amounts of 0.01 to 1% by weight, more preferably 0.05 to 1% by weight, and especially 0.05 to 0.6% by weight, based on the white pigment.
The paper coating composition used in the method according to the invention can, be prepared by mixing the components in any desired sequence at temperature from 10 to 100xc2x0 C., preferably 20 to 80xc2x0 C. The components here also include the customary auxiliaries which can be added to regulate the Theological properties, owl such as viscosity or water retention capacity, of the coating compositions. Such auxiliaries are, for example, natural binders, such as starch, casein, protein or gelatin, cellulose ethers, such as carboxyalkylcellulose or hydroxyalkylcellulose, alginic add, alginates, polyethylene oxide or polyethylene, oxide alkyl ethers, copolymers of ethylene oxide and propylene oxide, polyvinyl alcohol, water-soluble condensation products of formaldehyde with urea or melamine, polyphosphates or polyacrylic acid salts.
The coating composition used according to the method of the present invention is preferably used to produce coated printed or writing paper, or special papers such as cardboard or photographic papers.
The coating composition used according to the method of the invention can be applied to the substrate by any conventional process, for example with an air blade, a coating blade, a roller, a doctor blade or a rod, or in the size press, after which the coatings are dried at paper surface temperatures in the range from 70 to 200xc2x0 C., preferably 90 to 130xc2x0 C., to a residual moisture content of 3-8%, for example with infra-red driers and/or hot-air driers. Comparably high degrees of whiteness are thus achieved even at low drying temperatures.
By the use of the method according to the invention, the coatings obtained are distinguished by optimum distribution of the dispersion fluorescent brightener over the entire surface and by an increase in the level of whiteness thereby achieved, by a high fastness to light and to elevated temperature (e.g. stability for 24 hours at 60-100xc2x0 C.) and excellent bleed-fastness to water.
In a second preferred aspect, the present invention provides a method for the fluorescent whitening of a paper surface comprising contacting the paper in the size press with an aqueous solution containing a size, optionally an inorganic or organic pigment and 0.1 to 20 g/l of a fluorescent whitening agent having the formula (1). Preferably, the size is starch, a starch derivative or a synthetic sizing agent, especially a water-soluble copolymer.
In a third preferred aspect, the brighteners defined above are of particular importance for the treatment of textile fabrics. The treatment of textile substrates is advantageously carried out in an aqueous medium in which the particular optical brighteners are present in a finely divided form (suspensions, so-called microdispersions and in some cases solutions). Dispersing agents, stabilisers, wetting agents and further auxiliaries can optionally be added during the treatment.
The treatment is usually carried out at temperatures of from about 20xc2x0 to 140xc2x0 C., for example at the boiling point of the bath, or in the region thereof (about 90xc2x0 C.). For the finishing, according to the invention, of textile substrates it is also possible to use solutions or emulsions in organic solvents, as are used in dyeing practice in so-called solvent dyeing (pad-thermofix method and the exhaustion dyeing process in dyeing machines).
The optical brighteners which can be used according to the present invention can also be employed, for example, in the following use forms:
(a) In mixtures with so-called xe2x80x9ccarriersxe2x80x9d, wetting agents, softeners, swelling agents, antioxidants, light stabilisers, heat stabilisers and chemical bleaching agents (chlorite bleach and bleaching bath additives).
(b) In mixtures with crosslinking agents and finishing agents (for example starch or synthetic finishing agents) and also in combination with very diverse textile finishing processes, especially synthetic resin finishes (for example crease resistant finishes such as xe2x80x9cwash-and-wearxe2x80x9d, permanent press and xe2x80x9cno-ironxe2x80x9d), and also flame resistant finishes, soft handle finishes, anti-soiling finishes or anti-static finishes or antimicrobial finishes.
(c) As additives to various soaps and washing agents.
(d) In combination with other substances having an optical brightening action.
If the brightening process is combined with textile treatment or finishing methods, the combined treatment can in many cases advantageously be effected with the aid of corresponding stable formulations which contain the compounds having an optical. brightening action in a concentration such that the desired brightening effect is obtained.
In certain cases, the full effect of the brightener is achieved by an after-treatment. This can be, for example, a chemical treatment (for example acid treatment), a thermal treatment (for example heat) or a combined chemical/heat treatment.
The amount of the optical brighteners to be used according to the invention, relative to the material to be optically brightened, can vary within wide limits. A distinct and durable effect can already be achieved with vary small amounts and in certain cases, for example, with amounts of 0.03% by weight. However amounts of up to about 0.5% by weight can also be used. For most cases of interest in practice, amounts of between 0.05 and 0.5% by weight relative to the material to be brightened, are preferably of interest.
In a fourth aspect of the invention, the optical brighteners are also especially suitable as additives for washing baths or to industrial and household washing agents and they can be added in various ways. They are appropriately added to washing baths in the form of their solutions in water or organic solvents or also in a state of fine division as aqueous dispersions or slurries. They, or their components, are advantageously added to household or industrial washing agents at any phase of the manufacturing process of the washing agent, for example to the so-called xe2x80x9cslurryxe2x80x9d prior to spray-drying of the washing powder or during the preparation of liquid washing agent combinations. The compounds can be added both in the form of a solution or dispersion in water or other solvents and also without auxiliaries in the form of a dry brightener powder. However, they can also be sprayed, in the dissolved or pre-dispersed form, onto the finished washing agent.
Washing agents which can be used are the known mixtures of detergent substances, such as, for example, soap in the form of chips and powders, synthetic products, soluble salts of sulphonic acid half-esters of higher fatty alcohols, arylsulphonic acids, which are substituted by higher alkyl and/or polysubstituted by alkyl, carboxylic acid esters with alcohols of medium to higher molecular weight, fatty acid acylaminoalkyl- or aminoaryl-glycerol-sulphonates, phosphoric acid esters of fatty alcohols and the like. So-called xe2x80x9cbuildersxe2x80x9d which can be used are, for example, alkali metal polyphosphates and alkali metal polymeta-phosphates, alkali metal pyrophosphates, alkali metal salts of carboxyethylcellulose and other xe2x80x9csoil redepositon inhibitorsxe2x80x9d, and also alkali metal silicates, alkali metal carbonates, alkali metal borates, alkali metal perborates, nitrilotriacetic acid, ethylenediamine-tetraacetic acid and foam stabilisers, such as alkanolamides of higher fatty acids. Furthermore, the washing agents can contain, for example: antistatic agents, superfatting skin protection agents, such as lanolin, enzymes, antimicrobial agents, perfumes and dyestuffs.
The brighteners have the particular advantage that they are also effective in the presence of A active chlorine donors, such as, for example, hypochlorite and can be used without substantial loss of the effects in washing baths with non-ionic washing agents, for example alkylphenol polyglycol ethers. Also in the presence of perborate or peracids and activators, for example tetraacetylglycoluril or ethylenediamine-tetraacetic acid are the new brighteners very stable both in pulverulent washing agent and in washing baths.
The brighteners according to the invention are added in amounts of 0.005 to 2% or more and preferably of 0.03 to 0-5%, relative to the weight of the liquid or pulverulent ready-to-use washing agent. When they are used to wash textiles made of cellulose fibres, polyamide fibres, cellulose fibres with a high grade finish, wool and the like, wash liquors which contain the indicated amounts of the optical brighteners according to the invention impart a brilliant appearance in daylight.
The washing treatment is carried out, for example, as follows:
The indicated textiles are treated for 1 to 30 minutes at 5xc2x0 to 100xc2x0 C. and preferably at 25xc2x0 to 100xc2x0 C. in a wash bath which contains 1 to 10 g/kg of a composite washing agent containing builders and 0.05 to 1% relative to the weight of the washing agent, of the brighteners claimed. The liquor ratio can be 1:3 to 1:50. After washing, the textiles are rinsed and dried in the customary manner. The wash bath can contain, as a bleach additive, 0.2 g/l of active chlorine (for example in the form of hypochlorite) or 0.1 to 2 g/l of sodium perborate.
The brighteners according to the invention can also be applied from a rinsing bath with a xe2x80x9ccarrierxe2x80x9d. For this purpose the brightener is incorporated in a soft rinsing agent or in another rinsing agent, which contains, as the xe2x80x9ccarrierxe2x80x9d, for example, polyvinyl alcohol, starch, copolymers on an acrylic basis or formaldehyde/urea or ethylene-urea or propylene-urea derivatives, in amounts of 0.005 to 5% or more and preferably of 0.2 to 2%, relative to the rinsing agent. When used in amounts of 1 to 100 ml, and preferably of 2 to 25 ml, per liter of rinsing bath, rinsing agents of this type, which contain the brighteners according to the invention, impart brilliant brightening effects to very diverse types of treated textiles.
In a fifth aspect of the invention, the compounds of formula (1) are also suitable for removing stain in a photographic material which comprises a silver halide photographic light-sensitive material and, more detailedly, to a process thereof, wherein the improvement is made on the prevention of a colour stain and particularly the prevention of a colour dye stain caused in the course of processing said silver halide photographic light-sensitive material by a colour developer and a bleach-fix bath.